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Copyright © Claytex Services Limited 2015

Multi-domain vehicle dynamics models for

Driver-In-the-Loop simulation

Systems Engineering Specialists


Claytex Services Limited

• Based in Leamington Spa, UK

– Office in Cape Town, South Africa

• Established in 1998

• Experts in Systems Engineering, Modelling

and Simulation

– Focused on physical modelling and

simulation using the open standards:

Modelica and FMI

• Business Activities

– Engineering consultancy

– Software sales and support

• Dassault Systemes

• rFpro

– Modelica library developers

– Training services

• Global customer base


What does Claytex do?

• Engineering consultancy

– Process development and improvement

– Model development and analysis services

– Integration of models with HiL, MiL, DiL tools and processes

• Optimisation of models for real-time fixed step simulation

• Coupling to Driver-in-the-loop platforms including commercial solutions from

Ansible Motion and McLaren Applied Technologies and bespoke solutions

• Software distributors

– Dassault Systemes partner specialised in Systems Engineering tools:

Dymola, Reqtify, ControlBuild, AUTOSAR Builder and CATIA Systems

portfolios

– rFactor Pro: DiL simulators for vehicle dynamics engineering

• Modelica library developers

– Solutions for: Engines, Powertrain Dynamics, Vehicle Dynamics, DiL

and related libraries compatible with Dymola

• FMI tool developers

– Including the FMI Blockset for Simulink


Introduction

• Driving simulators increasingly used in both

Motorsport and Automotive

• Originally introduced in Motorsport for driver

training

• Allows tests to be completely safe and in

repeatable conditions

• Due to testing restrictions now used to evaluate

new designs, new technologies and work on car

setup before arriving at the race track

• Broad range of approaches to suit different

needs

– Desktop system

– Small motion systems with 3-4 dof

– Full motion platforms with 6 dof

• Entertainment systems

• Engineering development systems


Example Motorsport System

• Simulators for engineering development

• Ansible Motion Series 1 platform

– 6 degrees of freedom

– Large excursions possible on all axes

– High frequency range for realistic motion

cueing

• rFactor Pro graphics, sound and track

data

– Low latency and high bandwidth offering

the fastest video & audio pipelines

– Extensive range of tracks available for

Motorsport and Automotive applications

• Dymola based vehicle dynamics model

– Multi-domain vehicle model


Example Desktop System

• Able to evaluate baseline capability of a vehicle or enable detailed assessment and development of a

control system, steer-by-wire system, etc.

• Key features:

– rFactor Pro provides the core capability

• Range of test scenarios (race tracks, proving ground)

• High quality graphics on multiple monitors

– Dymola vehicle model

• Full MultiBody chassis model

• Multi-domain vehicle model

– Telemetry system

– Steering wheel

• Gaming systems or sophisticated handwheel motor

– Sensodrive, Ansible Motion, etc.

– 1 PC used for the complete simulator system

– Connect laptop with calibration and telemetry tools

– HiL system

• Concurrent, dSpace, etc.


Physics Model

• Has to provide an accurate representation of the

complete vehicle

– Tyres

– Suspension

– Powertrain

– Multi-domain system: mechanics, control,

electrical, fluids, etc.

• Has to run in real-time, typically 1kHz for a full

motion driving simulator

• Has to give the driver the right “feeling” about

the behaviour of the car

– Feedback through the steering wheel

– Transient behaviour


Dymola

• Component orientated, physical modelling tool

• Modelling and simulation of systems integrating multiple physical domains

• Based on Modelica

• Supports the FMI standard

• Application libraries to

model the whole car

• Part of the CATIA brand


Component Orientated Modelling

• Modelling and simulation of systems integrating

multiple physical domains

– Mechanics (1D, MultiBody), 1D Thermofluids,

Control, Thermal, Electrical, Magnetics and more

• Promotes extensive model reuse at component

and system level

– Components represent physical parts: valves,

gears, motor

– Connections between parts describe the physical

connection (mechanical, electrical, thermal, signal,

etc.)

• Store your own component and system models

in libraries to easily share and reuse them

across the business


• Models are defined using the Modelica modelling language

– A generic modelling language

– Design for convenient, component orientated modelling of complex multi-domain systems

– Models are defined as differential algebraic equations (DAE)

• A freely available, open source, standardised modelling language

• Developed and maintained by the Modelica Association

– An independent, international not-for-profit organisation

– Established in 1996

– Currently over 100 members from academia, tool vendors and industrial end-users

• Anyone can get involved

• The Modelica Standard Library contains basic models in many engineering domains


Model Definition

• Models are defined using the Modelica modelling language

• Symbolic manipulation automatically transforms the models

into efficient simulation code

• Can deliver real-time simulation performance of Vehicle

Dynamics models with over 100,000 equations (at 1kHz)

• Supports multi-threading to make full use of multi-core

machines

model Inertia

extends Interfaces.Rigid;

parameter SI.Inertia J=1 “Moment of Inertia”;

SI.AngularVelocity w “Angular velocity”;

SI.AngularAcceleration a “Angular acceleration”;

equation

w = der(phi);

a = der(w);

flange_a.tau + flange_b.tau = J * a;

end Inertia;


Modelica Application Libraries

• Air Conditioning

• Electric Power

• Engines

• FlexBody

• Flexible Bodies

• Flight Dynamics

• Fuel Cell

• Heat Exchanger

• Human Comfort

• Hydraulics

• Liquid Cooling

• Pneumatics

• Powertrain Dynamics

• Simulator

• Smart Electric Drives

• SystemID

• Terrain Server

• Thermal Power

• TIL Suite

• Vapor Cycle

• Vehicle Dynamics

• VDLMotorsports

• XMLReader


Vehicle Dynamics for Motorsports

• VDLMotorsports Library

– Add-on to Vehicle Dynamics library

– Used in Formula 1, IndyCar, GP2, NASCAR and sports car

racing

• Includes adjustable suspension

– Specify shim thickness to adjust track rod, pushrod, etc.

• Kinematic and compliant suspension models

• Includes setup and quasi-static experiments

• Real-time capable MultiBody models

• Open and extendible

• Simulator Library provides out-of-the-box integration with

rFactor Pro for DiL


Vehicle Dynamics for Road Cars

• Vehicle Dynamics Library

– Template based approach to modelling

• Library of MultiBody suspension

templates

– McPherson, double wishbone,

multi-link, trailing arm, …

– Open and extendible to allow you

to add your own templates

• Kinematic and compliant models

– Non-linear bushes or ideal joints

– Structural compliance effects

• Wide range of experiments

– Quarter car, half car, whole chassis, full vehicle

– Closed loop and open loop driver models

• Provides models for real-time simulation

• 3D Road Definition and support for rFPro Terrain Server and OpenCRG


Powertrain Modelling

• Engines Library

– Mean value and Crank angle resolved models

– 1D thermofluids for the air-path, fuel-path, cooling, lubrication

– MultiBody mechanics for complete engine

– Thermal network

• Powertrain Dynamics Library

– MultiBody mechanics for transmission and driveline

– Thermal effects in friction

– Variable fidelity models to support fast drive cycle simulation and

detailed driveability analysis


Hybrid Powertrains

• Batteries

– Parameter estimation functions to define the cell models

from test data capturing electrical, thermal and ageing

effects

– Cell models are equivalent electrical circuit models

– Model architecture to conveniently build the module and

pack models from a validated cell model

– 1D thermofluid approach for the cooling systems

• Electric Motors and Power Electronics

– Motor models for fast simulation or detailed transient

analysis

– Power electronics can be ideal power balanced models

or include switching effects

– Field orientated control built into motors

– Thermal effects in the power electronics and motors


Control Systems

• Control systems in Dymola

– Block diagrams

– Finite state machines

– Procedural code

• Dymola includes state of the art controller design tools

– Model inversion to support model based control design

• For example: use the same bicycle model as a reference model and in feed-forward design

– Linearisation of physical models

• Integrate existing controllers

– Import FMI compliant models

• FMI is an open standard for model exchange supported by over 50 engineering tools

• Simulink models can be compiled to be FMI compliant using

a Simulink Coder target provided with Dymola

– Import c-code

• Dymola supports the use of c-code within a Modelica model

– Export the Dymola model to be FMI compliant and use

in other tools

• e.g. FMI Blockset for Simulink, Silver, etc.

k=ratio

gain1 PI

PI

T=Ts

-

feedback1

k=kp

P add3

+1

+1

-1

+

k=ratio

gain2

axisControlBus


Driver-in-the-Loop Simulators

• Claytex have developed a set of solutions that enable Vehicle Dynamics

models to be used with rFactor Pro

– Simply plug the vehicle model in to a template and execute the build function

• Compiles model to work with McLaren Electronics vTAG and PTWinSim

environments

– Soft real-time environments

• Compatible with the HiL environments using the Dymola tools (dSpace,

xPC, etc.)

• Solution proven on several motion platforms

– Ansible Motion, McLaren Electronics, MOOG

• Also used for static simulation environments

• Supports full range of rFactor Pro features

– High Definition Terrain Server and multiple tyre contact points

– Collisions


Formula 1 2014 Powertrains

• Dymola is used by F1 teams, NASCAR

and IndyCar

• Using Dymola it was possible for

the teams to simulate the 2014

powertrain as part of a complete

vehicle model

– Engine performance and efficiency

– MGU-H and MGU-K strategies

– Thermal management of all systems

– Impact on vehicle dynamics of

higher torque output and delivery

• Why is Dymola popular in Motorsport?

– Extensive range of application libraries

– Based on Modelica which means the models are open and extendible

– Powerful modelling language to implement new ideas from first principles and explore the behaviour

– The same model can be shared across the team and deployed for different applications

• Desktop, HiL, SiL, DiL, trackside, …


Simulation experiment

Driver model

• Throttle

• Brake

• Steering

• Gears

Atmosphere

• Pressure

• Density

• Wind speed and

direction

Road model

• 3D road surface model

• Inclination

• Friction coefficient of

surface

Vehicle model

• Powertrain

• Chassis

• Brakes

• Tyres

World

• Coordinate system

• Gravity

• Animation settings


Vehicle model

• Vehicle Dynamics

– Multibody chassis

– Pacejka tyre models

– Aerodynamics

– Ground impact

• Brakes

• Powertrain

– Engines

• Power unit ICE and cooling

– Electrical libraries

• MGU-K

• MGU-H

• Energy Storage

– Driveline

– Gearbox


B

ride?

cam?

cam?

geometrygeometrygeometrygeometrygeometry

leftLinka?

rightLink?

Chassis and suspension

• Real-time model includes

– Heave spring

– Heave damper/inerter

– Roll damper

– Ride dampers

– Torsion bars

– Anti-roll bar


Animation of front suspension


ICE, MGU and Coolant System integration

• Parameterised mean value engine model is pressure charged by means of a mapped turbocharger and

integrated with the MGU-H and MGU-K in the power unit model below:

ICE

Cooling

systems

Pow

er

Unit


MGU and Energy Storage representation

MGU-K and MGU-H

• Electrical effects

– Internal resistance

– Heat losses

– Inductance

• Mechanical effects:

– Inertia

– Frictional losses

– Heat rejection

– Torque reaction into

MGU support

Energy Storage

• Equivalent Circuit model

– Internal resistance

– Diffusion limitation

– Thermal losses

– Resistance

– Capacitance

– OCV with temperature

& SOC dependency


Simulation results

• Ability to interface multiple

domains to understand the

whole system dynamics

• Multiple ERS control

strategies were evaluated

using physical system

models

• Models are real-time

capable and can be used

within a driver simulator


Driver-in-the-loop

• Dymola models can then be exported to run as

part of a driving simulator

– Run the model directly within rFPro

• McLaren Electronics vTAG or Podium Technologies

PTWinSim

– Run the model on a HiL system

• Concurrent, dSpace, etc.

• Technology also supports road car

applications

– Same motion platform with different cockpit

– Urban environments and proving ground rather

than race tracks to drive on

Videos from Ansible Motion and rFPro


Summary

• Modelica and Dymola can be used to create multi-domain vehicle models suitable for use in Driver-in-

the-Loop applications

– MultiBody vehicle dynamics models

– Mean value engine models

– Electrical and thermal models

– Control systems

• Using Dymola, new design ideas and concepts can be quickly modelled and compiled for use in the

simulator

– Enables real drivers to start evaluating these ideas at a very early stage in the development process

– The simulator usage increases and is brought earlier in to the development process

• Supports HiL integration to enable calibration and validation of real controllers


Contact

For further information please contact:

Mike Dempsey

Claytex Services Ltd.

Edmund House

Rugby Road

Leamington Spa

CV32 6EL

UK

Tel +44 1926 885900

Fax +44 1926 885910

[email protected]

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